Well, memory probably does get worse as you age, but, maybe its just something as simple as working harder, not eating more food, your body just isn't working as well.
When you're tired your brain certainly isn't working as efficiently. Then again theres also a limit to how much information you can take in, in a day, if you're just that busy, some stuff will get lost in the mix. Try eating a little better/more often, see if its simply tiredness/lack of correct nutrition. I'm sure its nuts that are supposed to by and large be good brain food, carry a pack with you and have a few between sessions, keep your energy levels a little higher and a pick me up before every meeting might help you remember the meeting a bit better.
Isn't that largely why therapists take notes, because its simply not feasable to remember everything said to patients throughout the day if you're seeing a lot of people. Do the same, take notes, then you can glance over them later in the day, a quick list of what you did, seeing the list later on will reinforce the memories so a day later, you'll have a better recollection of what you did.